1. Field of the Invention
The present invention relates to a driving support system for supporting driving operations for making a vehicle travel along a proper route on a road.
2. Description of the Related Art
A technique disclosed in JP-A-2005-324782 applies a yawing moment to a vehicle when the vehicle tends to deviate from a desired lane by controlling braking forces acting on the wheels of the vehicle to prevent the vehicle from deviating from a desired lane and to notify the driver that there is the possibility that the vehicle deviates from the lane. The technique changes the value of controlled variable, such as a threshold for off-lane avoidance control, taking into consideration obstacles beside the lane to achieve optimum off-lane avoidance control.
Patent Document 1: JP-A-2005-324782
Nothing is mentioned in JP-A-2005-324782 about simultaneously carrying out supporting operations for guiding the vehicle to a desired route and for avoiding obstacles. For example, when there is an obstacle on a lane to which the vehicle is to be guided, the technique disclosed in JP-A-2005-324782 executes an obstacle avoidance operation after the vehicle has completed changing the lanes. Therefore, it is possible that the start of the obstacle avoidance operation cannot be properly timed. Only either of the threshold for off-lane avoidance control and the threshold for obstacle avoidance control is used for driving support control at some point of time and at some position. Therefore, it is possible that driving support control is not executed for avoiding an obstacle after the vehicle has deviated from the lane when the obstacle is outside the threshold for deviation avoidance control. When the driving support control is executed on the basis of the threshold for obstacle avoidance control, there is the possibility that sharp driving support control is executed to avoid an obstacle because the threshold for ordinary off-lane avoidance control is ineffective. Such a mode of driving support control gives the driver a feeling of discomfort. Thus, the technique disclosed in JP-A-2005-324782 cannot make driving support for guiding the vehicle along a desired route and driving control for avoiding obstacles compatible.